Laundry machine and method



Feb. l5, 1966 w. K. coMPANs 3,235,082

LAUNDRY MACHINE AND METHOD Original Filed Aug. 14, 1957 '7 Sheets-Sheet1 Feb. l5, 1966 w. K. coMPANs 3,235,082

LAUNDRY MACHINE AND METHOD Original Filed Aug. 14, 1957 '7 Sheets-Sheet2 La zZLDT Wil/"mea" .ffar/ 50m/Dans Feb. 15, 1966 w. K. coMPANs3,235,082

LAUNDRY MACHINE AND METHOD Original Filed Aug. 14, 1957 'T Sheets-Sheet5 Awe zzZcU:7

-Wl//m'ea/ /Car/ 50m/nana I: j MM,%WQ%MV@MHHS Feb. 15, 1966 w. K.coMPANs LAUNDRY MACHINE AND METHOD '7 Sheets-Sheet 4 Original Filed Aug.14, 1957 LFE IZDT' W//mlea /ar/ Com/0am 77 TMJWHHE Feb. l5, 1966 w. K.coMPANs LAUNDRY MACHINE AND METHOD 7 Sheets-Sheet 5 Original Filed Aug.14, 1957 Mmmm LFE ZZQT' WAL/fried far/ 'omlbazz Feb. 15, 1966 w. K.coMPANs 3,235,082

LAUNDRY MACHINE AND METHOD Original Filed Aug. 14, 1957 7 Sheets-Sheet 6CYL /NDEF 7?. PM.

74 T/ME LFE :afar /W/fr/led' [Car] Com/bans Feb. 15, 1966 w. K. coMPANs3,235,082

LAUNDRY MACHINE AND METHOD Original Filed Aug. 14. 195'? '7 Sheets-Sheet7 WAY/fried [fari Com/nana United States Patent O 3,235,082 LAUNDRYMACHINE AND METIII) Wilfried Karl Comparis, St. Joseph, Mich., assignorto Whirlpool Corporation, St. Joseph, Mich., a corporation of DelawareContinuation lof application Ser. No. 678,224, Aug. 14,

1957. This application Apr. 23, 1962, Ser. No. 192,021

16 Claims. (Cl. 21d-78) This application is a continuation of mycopending application Serial No. 678,224 tiled August 14, 1957, nowabandoned.

The present invention relates to improvements in laundering machines andmore particularly to an improved balancing device and method forautomatically correcting imbalance in rotors such as laundering machinecontainers which are spun at high speeds to centrifugally extract fluidfrom laundered articles.

Centrifugal extraction is a commonly used expedient in launderingmachines, and especially in automatic home laundering machines for theextraction of washing fluid from the laundered articles after thewashing and rinsing periods. At the termination of a launderingoperation, the laundering container is spun at a high speed, preferablywithout manually arranging the clothes and articles being washed toobtain balancing. Even if an attempt is made to distribute the launderedarticles within the container, a dynamic balance of the container isditlcult to achieve.

A relatively high spinning speed is used for centrifugal extraction oflaundering fluid from the articles for a drying operation and the wetarticles have a considerable weight. It is, therefore, imperative thatthe container with the articles therein be balanced to prevent anexcessive vibration and movement of the appliance across the floor. Ifany substantial unbalance is present, correction of this imbalance isnecessary before the machine reaches operating speed. This is frequentlyditiicult, inasmuch as the location of unbalance and amount of unbalancevaries for each load and for each spin cycle in a complete cycle ofoperation. The amount of unbalance changes as fluid is being extractedfrom the articles.

It is, therefore, an objective of the present invention to provide animproved method and apparatus for reducing dynamic unbalance in rotorssuch as laundy container to permit rotation at high `speed withoutexcessive vibration and shaking of the machine.

It is a further object of the invention to provide an improved methodand apparatus for balancing laundry machine containers wherein theunbalance caused by the volume of washing liquid which will be extractedin the early stages of rotation is taken into consideration so as toavoid applying improper corrective masses, and correction is made onlyfor the unbalance of the articles less the bulk of extracted liquid.

Another object of the invention is to provide a method and apparatus forapplying balancing masses to a rotating laundry container as unbalancedforces are detected, and wherein excessive vibration is not generateddue to rotational speed before the corrective masses are applied.

A further object of the invention is to provide an apparatus and methodfor the balancing of the containers for drying laundered articleswherein the excessive lluid in the articles is first removed beforeapplying c-orrective counter balancing masses. i

A still further object of the invention is to provide an apparatus andmethod wherein balancing masses are applied to a rotating launderingcontainer while the container is accelerating to the operational speed,the acceleration interrupted, and additional balancing masses applied tothe container.

ICC

A still further object of the invention is to provide an apparatus andmethod for the balancing of a laundry drying container wherein the speedof rotation of the container is rapidly returned to tumbling speed whenan excessive condition of unbalance occurs.

A further object of the invention is to provide improved mechanism whichwill act to automatically correct unbalance in a rot-ating laundrycontainer and which is well adapted to use with an automaticallycontrolled laundry machine which performs its washing, rinsing anddrying operations in a predetermined controlled time sequence.

Other objects and advantages will become more apparent in connectionwith the teaching of the principles of the invention in the disclosureof the preferred embodiments thereof in the specification, claims anddrawings, in which:

FIGURE 1 is a vertical sectional view taken through a laundry machinedrum embodying apparatus for balancing the drum with parts removed forclarity;

FIGURE 2 is a rear elevational view of the laundry drum of FIGURE 1 withparts of the drive mechanism removed;

FIGURE 3 is a rear elevational view of the laundry drum illustrating thedrive mechanism to be used for rotating the drum;

FIGURE 4 is a vertical sectional view taken along line IV--IV of FIGURE3 with parts removed for better illustrating certain features ofconstruction;

FIGURE 5 is a detailed fragmentary elevational view taken from the backof the machine illustrating part of the unbalance detection mechanism;

FIGURE 6 is a detailed fragmentary side elevational view illustratingthe unbalance detection mechanism of FIGURE 5;

FIGURE 7 is a diagrammatic presentation of the electrical circuitry usedfor detecting and correcting the unbal-ance of the laundry container;

FIGURE 8 is a graph illustrating operation of the machine during anunbalance correction period with the speed of rotation of the cylinderplotted against time; and,

FIGURE 9 is a graph illustrating the rotation ofthe cylinder against thefull time of operation with a chart located beneath the graph andcorresponded to it in time to illustrate the function of variousoperational machine elements over the period of operation of themachine.

FIGURES 1 through 6 lillustrate apparatus which is utilized in the`method of correction of unbalance in a laundry container employing theprinciples and method of the present invention. It will be recognized bythose skilled in the art that apparatus of various vtypes may be used inthe detection of the location and 'amount of the unbalance forces `andthe actual correction of unbalance. The present invention utilizes thisapparatus in a unique manner and in combination with apparatus for animproved mechanism and method for -correcting unbalance. In FIGURES 7through 9 the electrical circuitry used in the control mechanism isillustrated as well as `the operation of the machine to teach thearrangement of the preferred `embodiments and the principles of theinvention.

As shown in FIGURES 1 through 4, apparatus for deteoting the amount andlocation of unbalance and applying a corrective force are illustratedemployed in combination with la laundry machine which is preferably ofthe automatic type. In the machine, the functions of t-he machine, aswell as the unbalance detection and correction apparatus are controlledby a presettable sequential time cycle control which automaticallycauses the machine to proceed through its program of operations witheach of the operational elements performing its function at apredetermined time and for a predetermined period of time in accordancewith the method of the present invention.

The laundering machine is illustrated in FIGURES 1 through 4 as having adrum l2 which is rotatable `about a horizontal axis. The drum isprovided with a rear wall 14 which is joined at its outer peripheraledge to a wraparound cylindrical outer wall lo. The front end of thedrum 12 is formed by an annular wall 13 which is secured at i-ts outerperipheral edge to the front end of the cylindrical outer wrap-aroundwall 16 and which has an outwardly extending flange 66 provided with acircular opening 2t) at the front end for the insertion and removal ofarticles such as clothes 22, which `are laundered within the drum. Itwill be understood that the drum is preferably adapted for launderingclothes and the space within the drum defines a laundering zone whereinthe functions of washing, rinsing and drying are perfor-med, `althoughthe drum may be used for drying alone. It will be apparent that thesewashing and rinsing functions are performed with the aid of auxiliaryelements for supplying the Washing fluid, for agitating the tluid andthe like. These elements -are n-ot shown in detail for purposes of:simplicity of the Idrawings. While the drum is illustrated as rotatingabout a horizontal axis, it will be understood that launderingcontainers of different sizes and shapes and operating in differentpositions may be utilized .adapting the principles of the invention to:maintain the container in balance for high speed rotation.

Rotation of the container or drum 12 is employed for the drying functionwherein the drum 12 is rotated at a relatively high speed forcentrifugally extracting the washing liquid from the clothes 22. Inorder to provide for the escape of washing fluid which is removed fromthe clothes 22, the outer wall 16 of the drum is preferably perforatedwith openings (not shown), in locations intermediate of the balancinguid-containing compartments 24, 26 and 28, FIGURES l and 2. To catch thelaundering lfluid `as it is thrown outwardly from the drum i2 through`the perforations. a. surrounding ytub or water container is providedwith -a suitable outlet leading to a drain.

The overall machine is preferably of the automatic type and is housedwithin a cabinet, not shown, upon which is mounted a control for .a-sequential time control of the cycle of operations, which may bemanually presettable to start ythe machine through its sequence ofevents.

In a machine of the type illustrated, a drum l2 is utilized forcontaining the clothes 22 for the washing, rinsing and drying functionsand may be of the type that is known as a combination machine. Thecabinet will enclose the entire working mechanism and a portion of afront wall 30 of the cabinet is shown in FIGURE 1. The front wall isprovided with a ldoor 32 which opens to provide access `through thefront opening 2@ of the drum. The d-oor is illustrated as preferablyprovided with an auto- -matic electrically operated latch 34 whichprevents accidental opening of the `door at high speeds and the controlfor the latch 34 will be described in connection with the circuitdiagrams of FIGURES 7 and 8. The drum 12 is rotatable on its horizontalaxis through a range of speeds which are controllable by the sequentialtime cycle control mechanism. One basic speed is a tumbling speed'during which time the varticles of clothing 22 will tumble from themaximum height within the drum l2 yto the base of the drum. Anotherspeed will be full spin-drying speed, also referred to herein asoperating speed, wherein the articles remain in one .place against theouter wall 16 of the drum, held there by centrifugal force. At .thisspeed, -the moisture or laundering yfluid is spun from the clothes andforced therefrom by centrifugal force.

The drum is rotatably supported on a cantilever shaft 3d rigidly securedto the center of the rear wall 1d. An inner wall y38 is spaced from therear wall Elfi to lend rigidity to Vthe connection between the drum andthe shaft and for aid-ing in supporting the weight of the drum whichmust support the clothes.

The shaft is supported by spaced bearings 4x2 and 44 which are carriedin a .ln-rotatable sleeve do. The bearing sleeve 46 is completelysuspended in a resilient material such as rubber 48, which extendsannularly .around the sleeve and is carried within a hollow hub 50.rThis permits unbalance vibration or oscillation of the sleeve 46 and ofthe shaft 36 and its supported drum 12. This vibration is detected forpurposes of correcting the unbalance and .applying corrective balancingmasses.

The hub Sil which supports resilient rubber carrier 48 for the bearingsleeve 46, is mounted on the frame at the machine as shown in part asrepresented by rear supporting frame work 52.

Still referring to FIGURES l and 2, the balancing mechanism for applyingcorrective balancing masses will be described. The balancing liquidcompartments 24, 26 and 28 are shown as extending across the outercircum* ferential wall lr6 of the drum with each compartment havingindividual end walls 5d and 55 with an inner wall 58 and an outer wall59. Liquid such as water, is filled into a selected compartment orcompartments in an amount to counterbalance unbalanced masses. Forexample, in FIGURE 2, the articles of clothing 22 lie in a group betweenthe compartments 24 and 28. To counterbalance this weight, liquid islled into the balancing compartment 26 to counterbalance the weight ofthe clothing 22 and bring the drum into balance. If the clothes 22 areweighted so that complete filling of compartment 26 will supply aninsuicient corrective force, the speed then attained is the maximumallowed and further acceleration is stopped.

During the rotation of the drum 12, at speeds above tumbling speed, thefluid in the compartments will be centrifugally held against the outerwall 59 of the compartments. When the drum is slowed down to a tumblingspeed, the fluid will flow against the inner wall 58 of the compartmentwhile it rotates through the upper portion. The fluid escapes throughthe compartment outlet port 6d, as shown for the compartment 24. Ashield 62 forming a drain cup is positioned over the outlet port 60. Acylinder iiange collar ed is secured to the flange 66 around the opening2u in the front wall 18 of the cylinder and held in place by a clampring 68. This collar 64 and clamp ring 68 form a channel with front wall18 to guide the water into the sump and prevent Contact with theinterior of the cylinder r2 and wetting the spun dry clothing load.

Balancing uid or water is admitted to the compartments during rotationof the drum 12. The water enters through a compartment inlet port '79 inthe end wall` 54 of the compartment. The water flows to the inlet port'7th through a passageway 72 formed between the rear wall 14 of the drumand an elongated channelshaped baie wall 74 secured to the inner surfaceof the rear wall to provide the passageway. Water enters the passageway72 through a port 76 in the rear wall 14 of the drum which communicateswith an outlet opening 78 in the annular concentric water distributingring 80.

Additional water distributing rings S2 and 8d are provided for each ofthe other balancing compartments 26 and 28. Openings lead from each ofthe rings 82 and 84, which are concentric with the drum, intochannelshaped baie plates 86 and 33 which lead outwardly through ports9h and 92 into the balancing compartments 26 and 23. Thus, when water isdeposited in either of the rings Si), 32 or 845, it will flow outwardlyinto the*y balancing compartment to which the ring connects.

Balancing liquid is directed to the distributor rings from a balancingliquid conduit 94 leading to a balancing` liquid manifold 96. Liquid,which may be in the form of water, is supplied from a pump 93 which isshown diagrammatically in FIGURE 1, and may be controlled by thesequential time control mechanism, as will be described in connectionwith FIGURE 8. The liquid manifold 96 and associated parts is shown in atrue position in FGY RE 2, and rotated for the purposes of illustrationin FlGURE 1.

The flow of balancing water from the manifold 96 is regulated bysolenoid valves 111i), 1112 and 104. The valves, when opened, permit theflow of water through balancing fluid nozzles 1116, 1il8 and 114i, asshown in FIGURES 1 and 2. The water flows through vacuum breakers 112,114 and 116 which have ends 113, 120 and 122 discharging into therespective annular rings 30, 82 and 84.

Thus, by selective operation of the solenoid valves i), 1412 and 104,balancing water is fed to one or more of the balancing compartments 24,26 or 28.

In FIGURES 3 and 4, portions of the enclosing cabinet are shown with thecabinet having a supporting basey 126 and side walls 128 and 13). Feet132 and 134 project from the base 126 of the cabinet to support it. Todrive the drum 12 within the cabinet in rotation, a drive pulley 136 issecured to the drum supporting shaft 36 in the manner shown in FIGURES 1and 3. The pulley 136 is of the V-type and is driven by a V-belt 138.The V-belt is driven by passing over a driving pulley 140 secured to anidler shaft 142. The shaft 142 is driven by a larger pulley 144, drivenby a belt 146 which in turn is driven by a driving pulley 14.8 of avariable speed drive 147. The driving pulley 148 of the variable speeddrive is shown in FIGURES 3 and 4, mounted on a shaft 150. Also mountedon the shaft is a driven pulley 152 which is driven by a drive belt 154passing over the drive pulley 156 of an electric motor 153. The electricmotor is mounted on the base 126 of the cabinet and is suppliedelectricity to be operated by the presettable sequential control system.The drive pulley 156, which is mounted on a drive shaft 160 of theelectric motor, is located next to a fan drive pulley 162 which drives abelt 164 leading up to the air circulating fan, which is not shown. Thisfan is used to circulate air through the drum 12 in the event themachine is adapted to perform a complete laundering operation whereinthe last step will complete the drying of the clothes by circulating theheated air therethrough.

The motor and pulleys are suitably suported on frame work within thecabinet and the pulleys 160 and 144, mounted on the idler shaft, areurged in a direction to tension the belts 133 and 146 by a compressionspring 166. The compression spring bottoms against a washer 168adjustably positioned by a nut 17) on a spring supporting rod 172. Therod 172 is mounted on a pin 174 which is located on the frame, and thespring 166 urges a shaft bracket 176 to the right, as shown in FIGURE 3,to maintain a tension on the belts, The shaft 142 is supported on thepivoted arm 178 which is also pivotally supported at its base on apivotal link 180. Spring 182, connected between the idler shaft 142 anda bracket 184 on the frame, aids in maintaining tension in the belts 138and 146.

The variable speed drive pulleys 148 and 152 function to change thedrive ratio between the drive motor 158 and the drum 14. This variablespeed drive may take varying forms and is shown in the form of a pulleydrive which is utilized because of its simplicity and suitability to usewith the amount of power which must be transmitted and the spaceavailable. The pulleys 148 and 152 constitute sheave plates which aremounted on a common shaft 150 and the inner wall 186 of the pulley 148and the inner wall 188 of the pulley 152 are movable with respect totheir opposing pulley walls 190 and 194. For example, as the inner wall186 moves away from the wall 190 to reduce the effective drivingdiameter of the pulley 148, the wall 188, which is attached to wall 136simultaneously moves toward its opposing wall 154 to increase theeifective diameter of pulley 152. Movement of the pulley walls iseffected by pivotal movement of a supporting yoke 192 which supports theshaft 150 carrying the pulleys. The yoke is pivotally supported on a pin194 and pivotal position is influenced by a cable 196 and a spring 198,both of which are attached t0 a pin 200 on the free end of the yoke 192.

The tension spring 198 is connected at one end to the pin 21H) on theyoke 192 and at the other end to a fixed bracket 202 which is shownsecured to the motor frame. The cable 196 pulls the yoke 192 in adirection opposing the action of the spring 198 to pivot the yoke 192 ina clockwise direction, as shown in FIGURE 3. The end 204 of the cable islooped over -a finger 206 on a speed control Winch pulley 2118. Thecable 196 passes over an idler pulley 210 and the end 204 is wound onthe winch pulley 208 which is rotated by a speed control drive motor212, as shown in FIGURE 4 (similar to the copending application SerialNo. 676,815 tiled August 7, 1957, no w U.S. Patent 2,942,447 owned by myassignee).

The speed control pulley 20S acts as a winch winding the cable 196 as itis driven by the motor to pivot the yoke 192 and gradually increase thespeed of rotation of the laundry drum. The speed control motor 212operates for a predetermined length of time as determined by thesequential time control switch and when it is automatically stopped, thedrier drum will have reached operating speed for centrifugally dryingthe articles therein.

For decreasing the speed of the drier drum by increasing thetransmission ratio of the variable speed control assembly 147, thisspeed control winch pulley 208 is released to release the cable 196whereupon the tension spring 198 will rapidly swing the yoke 192 back tothe left, as shown in FIGURE 3. Release of the speed control pulley 208is obtained by release of a clutch arm 214 which controls a clutchengaging the speed control motor 212 to the winch pulley 20S. The clutcharm 214 is actuated by a solenoid 216 which has its plunger 218connected to the clutch arm 214. When the solenoid 216 is electricallyenergized, the plunger core 218 moves the clutch arm 214 to an engagedposition and the speed control Winch 208 is rotated. When the solenoid216 is deenergized, a coil compression spring 220 rapidly moves theclutch arm 214 to disengaged position thereby releasing the winch pulley208. This rapidly moves the variable speed control pulleys 147 to theirlow speed position returning the speed of rotation of the drum totumbling speed.

Tumbling speed will be used for drying and a fast return to tumblingspeed is done at the end of a preliminary run during which excessivelaundering fluid is removed from the clothes and is done at any timewhen the vibration of the drum becomes excessive so as to cause walkingof the cabinet or cause damage to the operating mechanism.

For sensing unbalance of the drum, a deflector arm 226 is secured at abase end 228 to the bearing sleeve 46, FIGURES 1 and 5. Vibration of thedrum will cause vibration of the sleeve within its rubber support 48 tocause vibration of a free end 230 of the deflector arm 226.

The end 230 of the deflector arm 226 is positioned to actuate anunbalance detection switch 232. When the drum vibrates with unbalance,the end 230 of the deflector arm 226 Will actuate the switch 232operating an unbalance correction circuit in a manner which will bedescribed.

The deflector arm 226 is also adapted to operate an unbalance safetyswitch 234 with excessive unbalance and excessive deflection. The safetyswitch, when actuated, actuates a safety circuit to quickly return thespeed of rotation of the drum to tumbling speed in a manner which willbe described.

The unbalance detection switch 232 is firmly mounted on a bracket 236and the unbalance safety switch 234 is also fixedly mounted on a bracket238. An adjustable vertical bar 237 limits the movement of the deflectorarm 4226 away from the switch and dampens vibrations.

The deiiector arm 226 in combination with the unbalance detection switch232, operates to detect unbalance and the arm will actuate the switchwhen the unbalance moves the arm against the switch. This will occurwhen the drum is in a rotational position so that `the location ofunbalance on the drum is substantially diametrically opposite thedirection in which deflector arm 226 extends. Thus, the location of theunbalance will be determined and the balance correction compartment orcompartments which are opposite this location of imbalance must beiilled with water. To insure filling the correct compartment, theunbalance switch 232 completes a circuit only to the valve whichsupplies water to the correct balancing compartment.

The selective closing of the correct circuit is obtained by the use of acommutator ring 240, FlGURES 1 and 7.

The commutator ring 240 is secured at the end of the bearing sleeve 46in order to be xed with respect to a rotating commutator brush 242 whichrotates with the drum shaft 36, and which is connected in series withthe unbalance detection switch 232. Thus, with reference to FIGURE 7,whenever the unbalance detection switch 232 is actuated and closed, acircuit will be completed through the commutator ring segment which isin electrical circuit with the correct valve solenoid controlling theflow of water to the balancing compartment which will correct theunbalanced condition.

For example, if the unbalance load is created by the articles 22 withinthe drum 12, as shown in FIGURE 2, the balancing compartment 26 must beiilled. Assuming that the distributing ring 82 leads to the compartment26, the solenoid valve 102 must be opened. This will automatically occurbecause the detlector arm 226 will actuate the switch 232 when the brush242 is in electrical engagement with the commutator segment 244 which isconected to the solenoid 102- If the unbalance occurs at a differentlocation in the drum, the dcfiector arm 226 will actuate the unbalancedetection switch 232 when the commutator brush 242 is in contact withthe proper segment of the commutator ring which actuates a solenoidValve to distribute Water to the correct balancing compartment. Thus, abalancing force will be applied which will automatically correct theunbalanced condition. Furthermore, the unbalance detection switch 232will be actuated for each rotation of the drum as long as the unbalancedcondition exists and water will be fed to the compartment until thecorrective force caused by water in the balancing compartment correctsthe unbalanced condition.

As indicated in FlGURE 7, the unbalance detection switch 232 ispreferably a time delay switch so that water will ow to the balancecorrecting compartment in a steady flow. The unbalance detection switch232 is also provided with dual contacts so that normally open contact232a controls the circuit through the commutator segments to the watervalves and normally closed switch contacts 232b control the circuit tothe speed control 212. Contacts 232b are normally closed so that eachtime the switch 232 is actuated, due to unbalance of the drum, the-circuit to the speed control motor 212 is broken.

As shown in FIGURE 8, a stopping of the speed control motor 212 duringthe correction of the unbalance condition temporarily terminatesacceleration of the speed of the drum. The inclined graph line 246illustrates the operation of the drum during its balancing run. The drumstarts to accelerate at `point 248 and the horizontal break 250 in theline 246 indicates a period of speed unbalance correction. During thisperiod, the drum stops accelerating and continues to operate at aconstant speed while balancing mass, in the form of water supplied tothe balancing compartments are being applied. In accordance with themethod of the present invention, this prevents increase in the vibrationcaused by the unbalanced condition, and acceleration does not resumeuntil the unbalanced condition is corrected.

Operation at an intermediate speed may continue throughout apredetermined centrifuging cycle, as determined by the cycle controller268, if conditions of unbalance continue throughout this period.Theunbalance detection switch 232 has dual contacts wherein contact 232gcontrols the circuit through the commutator segments to the water valvesand normally closed switch contacts 23211 control the circuit to thespeed control motor 212. Contacts 23211 are normally closed so that eachtime the switch 232 is actuated, due to unbalance of the drum, thecircuit to the speed control motor 212 is broken. The period of timedelay begins with the first actuation of the switch by movement of thearm 226.

As is illustrated in FGURE 8 of the drawings, a stopping of the speedcontrol motor 212 temporarily terminates acceleration of the speed ofthe drum. The horizontal portion 250 on the graph of FIGURE 8illustrates operation at constant speed wherein the drum continues tooperate at constant speed during a balancing operation. Further, becausethe speed control pulley 2118 acts as a winch, it will not unwind unlessit is released by a clutch arm 214 under the control of a solenoid 216.Thus, the pulley 152 or movable sheave plate is held axially relative tothe other pulley 148 upon actuation of the sensing means, thereby toprovide operation thereof substantially at the speed at which saidpredetermined vibrations were sensed. The speed control drive motor issimilar to the motor illustrated in greater detail in U.S. Patent No.2,942,447.

Upon unbalance being sensed by the operator of switch 232, drumacceleration will be stopped one or more times as designated at points250 and 254 of the FlGURE 8 graph. This will not go on indefinitely. Ifthe rebalancing mechanism has reached the limit of its capacity by thecomplete filling of the appropriate rebalancing liquid compartment asdescribed hereinabove, then the drum speed will remain at this maximumallowed speed until the end of the centrifuging cycle, as determined bythe program switch 268. The drum will not drop back to tumbling speed onfailure of sufficient corrective force to rebalance the drum. Thislatter takes place only on the occurrence of another event; namely, theopening of a limit switch 234 as a result of vibration of such severityas to cause walking of the machine.

After the unbalance correction period, as represented by the horizontalline 251i, switch 232e, FIGURE 7, is again open while switch 23221 isagain closed. The period is determined by the time delay of the switch.However, a new time delay period will begin if the unbalance has notbeen fully corrected by the end of the first period.

rThe drum is then accelerated, as indicated by section 252 of the graphline 246. At a location 254 of the graph line an unbalance condition isagain encountered which causes actuation of the unbalance sensing switch232. During this time, switch contact 23211 closes to distributeadditional water to the balancing compartments and switch contact 232bopens to stop speed control motor 212 and cause the drum to rotate at aneven speed.

At the end of the line 254, after unbalance corrections have been made,the speed control motor 212 is again started, and the drum isaccelerated along the line section 256 until it reaches operating speedat 268. The drum may be rotated for a period of time at 260 until thefluid is extracted from the articles within the drum. The speed of thedrum is then rapidly dropped, as indicated by a line segment 262, totumbling speed as indicated by a line 264. The rapid reduction in speedindicated by graph line 262, is caused by the release of the clutch bythe clutch arm 214, FIGURE 4, to free the winch pulley 2118. rThisreleases the cable 1% whereupon the spring 198 rapidly pulls the arm 192to its return position to cause the speed control pulleys 147 to drop totheir low speed ratio.

The release of the speed control clutch by the clutch arm 124 Iis causedby deenergization of the solenoid 216. This is a result of the openingof switch 266 which is operated by the presettable sequential time cyclecontrol mechanism, shown diagram-matically at 268.

The presettable sequential control 268 may be of the type employed in anautomatic home appliance wherein a cam shaft carrying a plurality ofswitch operating cams `9 is rotated by a constant speed timer motor. Thecamoperated switches control individual circuits to operating elementsto cause their performance at a predetermined time to complete theprogram of operation. Switch 266 controls the circuit to the speedcontrol clutch solenoid 216 as wel as to the speed control motor 212 andthe valve operating solenoids 100, 102 and 104 for controlling `the flowof water to the balance correcting compartments.

When a washing or rinsing operation is first completed, the articleswithin the drum are saturated with water thereby greatly lmagnifying anyunbalance condition. The bulk of this saturating water is thrown offduring the iirst stages when the drum is being accelerated to attainopera tional spin-dry speed. During the time this first bulk of theWater is being extracted, the position, as well as the amount ofott-balance, may change rapidly. In accordance with the method of thepresent invention, no attempt is made to compensate for the firstunbalance forces to thereby prevent over-compensation or inaccuratecompensation.

The drum is first spun through a preliminary spin period at a speed lessthan spin-dry yoperating speed to remove the bulk of the water. Thisperiod of preliminary acceleration is shown in FIGURE 8 by the Section270 of the line which represents cylinder speed plotted against time.During this preliminary acceleration period, switch 272, as shown inFIGURE 7, is opened, as shown by the dotted line position of the switcharm. This switch may be controlled by the sequential time controlmechanism 268, and will be moved to the solid line position during thehigh speed run indicated by the line 246. However, in the open position,switch 272 permits vibration of the drum and prevents application ofcorrection forces. The rst acceleration run is made to a speed which issafely obtainable without attempting to compensate for ott-balance andwhich will not cause walking of the machine or damage to the parts byvibration.

When the tirst run is completed without balancing compensation, inaccordance with the method of the present invention, the speed of themachine is slowed down as indicated by the graph line 290 to tumblingspeed 274. At this tumbling speed the articles of clothing Within thedrum are permitted to distribute themselves which will have a balancingeffect. After the slowed tumbling redistribution speed, as indicated bythe line 274, the machine is acc-elerated along the line indicated bythe graph 246 during which time balance corrections are made. At thestart of this acceleration operational run, switch 272, FIGURE 7, isclosed so that unbalance corrections will be made.

At the beginning of the speeds above tumbling speed the door controlswitch 276 is also closed. This switch completes the circuit to theelectrical door lock 34 which prevents the door from being accidentallyopened during high speed operation.

As may be observed in FIGURE 9, preliminary low speed rotation of thedrum is indicated by the accelerationlines 27g and 280 made beforeoperational runs 282 and 284. The iirst operational run 282 is completedat the end of the washing period for removing the Wash water from theclothing. The second operational run 234 is made at the end of the rinseperiod for completely removing the rinse water from the clothing. Apreliminary rotational period, indicated by an acceleration line 286, issuticient in itself to remove the rinse water after an intermediaterinse and is followed by no operational period.

The lower portion `of FIGURE 9, indicates the operation of the differentelements of the machine over the entire program of operation. It will benoted that the motor functions during the entire operation and the speedof rotation of the drum is controlled by the speed control mechanism147.

The chart is self-explanatory with the word Pump indicating the pump forpumping the water from the tub after it has been extracted from thearticles of clothing within the drum. The term Water Selen indicates thecontrol valve for supplying rinse water to the articles within the drum.

Although the operation of the mechanism will be apparent from thedescription of structure and method of operation of the individualelements, a brief summary of operation will be helpful in understandingthe advantages and objectives of the invention.

The articles of clothing 22 are laundered within the drum 12 whichrotates on a supporting shaft 36. The shaft is supported on bearings 42and 44 which are mounted in a bearing sleeve 46 resiliently supported byrubber mounting 48.

At the end or a laundering operation, the bulk of the uid absorbed bythe articles is thrown off during a preliminary acceleration periodshown at 270 in FIG- URE 8. During this time, switch 272, FIGURE 7, isopen and no balance correction is applied to the drum. The drum is thendecelerated, as indicated by line 290 of the graph of FIGURE S, totumbling speed 274 during which period of time the clothes realignthemselves within the drum.

The drum is then accelerated along the line 246 of FIGURE 8 to anoperational speed 260. During the preliminary run 270, and theoperational balance-correcting run 246, the door lock switch 276 isclosed to prevent accidental opening of the door. The program of eventsis controlled by a presettable sequential time cycle control mechanism268 which operates the control switches.

During the operational run, switch 272 is closed in order that thecircuit may be completed to the water control solenoid valves 100, 102and 104 whenever unbalance exists. Balancing switch 232 is closed bylateral movement of the end 230 of the dellection arm 226 when the drumvibrates. Balancing water will be supplied automatically to thebalancing compartment 24, 26 or 2S to correct the unbalance. The flow ofbalancing water will be controlled by the completion of the electricalcircuit throug-h the solenoid valve 100, 102 or 104 by the brush 242engaged with the correct segment of the commutator ring 244 dependent onthe position of the drum when the unbalance vibration occurs to move thedeflector arm 226 against the switch 232. During the time the unbalancecorrection is being applied, the switch contact 23217 is opened to stopthe speed control motor 212, thus stopping the winch pulley 208. Whenthe balance has been corrected and the time delay switch contact 232bagain closes, the speed control motor 212 will again start to pull onthe cable 196 and gradually increase the speed transmission ratio of thepulleys 147.

If the unbalance vibration becomes excessive during any period of therun, the safety switch 234 will open, thus breaking the circuit to thesolenoid 216 releasing the clutch driving the winch pulley 208. Thiswill permit the spring 198 to take over and rapidly move the variablespeed drive pulleys 147 to the low speed position thus causing the speedof the drum to drop rapidly to tumbling speed.

At the end of the operational run, the speed control clutch operated bythe speed control arm 214, is also released thus slowing the drum totumbling speed.

As illustrated in FIGURE 9, throughout the sequence of operations duringthe operational program of the laundry machine, the elements arecontrolled by the presettable sequential time control switch. At the endof the laundering period, the drum is rotated through the preliminaryacceleration 278, and then slowed to permit the articles of clothing tobe rearranged. The drum is then accelerate-d to the operational speed282 for the spin-dry operation. The preliminary period is repeated at286 and 280 and the operational acceleration is repeated to bring thedrum up to operational speed at 284 at the end of a rinse period for thefinal spin-dry operatlon.

Thus, it will be seen that I have provided an improved method andapparatus for correcting unbalance in a rotor such as a container usedin an automatic laundry machine, which meets the objectives andadvantages hereinbefore set forth. The method is well adapted to usewith a domestic home laundry machine wherein the fluid is centrifugallyspun from the clothes at the end of the washing period and at the end ofthe rinsing periods.

The balancing can be accomplished in a minimum amount of time andwithout overbalancing, inasmuch as the original bulk of the washingWater is removed from the clothes before balancing correction forces areapplied. Further, the problem of walking of the machine cabinet ordangerous vibrations being reached is greatly reduced since theacceleration of the drum is stopped during the correction period. Also,corrections are applied as they occur during acceleration, thusachieving dynamic balance of the drum for safely rotating the machine atthe high speed spin-dry operational speed.

I have, in the drawings and specification, presented a detaileddisclosure of the preferred embodiment of my invention, but it is to beunderstood that I do not intend to limit the invention to the specificform disclosed but intend to cover all modifications, changes andalternative constructions and methods falling within the scope of theprinciples taught by my invention.

The embodiments of the invention in which an exclusive property orprivilege is claimed are defined as follows:

1. An automatic unbalance correction apparatus for a laundry containerunbalanced by laundered articles therein comprising a rotatable hollowlaundry container adapted to contain articles for a launderingoperation, a power drive for driving the container in rotation forapplying centrifugal force to remove vmoisture from the articlestherein, balancing means operative to make balancing corrections bychanging the weight of the container at a selected radial locationdetermined by the location of unbalance, unbalance detecting means forregulating said balancing means including means for determining thelocation of the imbalance and means for transmitting a control signal tothe balancing means whereby the location for operation of the balancingmeans will be selected and the unbalance correcte-d, and speed controlmeans gradually increasing the speed of the container to an operationalspeed and operatively connected to the unbalance detecting means andtemporarily stopping the increase of speed and maintaining anintermediate rotating speed during the operation of the balancing meansto correct an unbalanced condition, said intermediate rotating speedbeing a speed at which the unbalance is detected and timer regulatedmeans rendering the balancing means inoperative during a first rotativespeed of the container of a preliminary period when the bulk of water isbeing removed and also during a second rotative speed less than thefirst of subsequent periods when the clothes are rearranging themselvesto a balanced condition, said first rotative speed being less than thenormal rated operational speed of the container.

2. An automatic unbalance correction apparatus for a laundry containerunbalanced by laundered articles therein comprising a rotatable hollowlaundry container adapted to contain articles for a launderingoperation, a power drive for driving the container in rotation forapplying centrifugal force to remove moisture from the articles therein,balancing means operative to make balancing corrections by changing theweight of the container at a selected radial location, a speed controlfor the power drive operative to cause the drive to operate with agradual speed increase, and time delay means for the speed controlconnected to the balancing means and operative to render ineffective thebalancing means during a first relatively low speed rotation of thecontainer when the bulk of water is being removed, to reduce therotative speed below said first speed when the clothes rearrangethemselves to a balanced condition, to interrupt operation of the speedcontrol at the start of operation of the balancing means, and to againstart operation of the speed control after a predetermined timesufficient for an unbalance to be corrected.

3. The method of correcting unbalance in a rotating member such as alaundry container comprising the steps of first accelerating thecontainer to a preliminary centrifuging speed to extract a portion ofthe fluid in the articles, then secondly accelerating the container inrotation toward an essentially full operating speed for extraction ofother uid portions, detecting unbalance in the container during thesecond acceleration, applying corrective balancing masses to thecontainer when an unbalance condition is detected only after completionof said first acceleration step, temporarily terminating the secondacceleration of the container when the unbalance is detected andoperating and maintaining the container rotatably at a constantintermediate centrifuging speed while corrective balancing masses arebeing applied, said intermediate centrifuging speed being the speed atwhich the unbalance is detected, and immediately slowing the rotation ofthe container to a tumbling speed below said preliminary centrifugingspeed when an excessive unbalance of a predetermined magnitude isreached.

4. The method of centrifugally extracting fluids from wet fabricscarried within a revoluble receptacle comprising, extracting the bulk ofabsorbed uid from said fabrics by accelerating said receptacle to afirst preliminary centrifuging speed unmolested of an unbalancecorrection, lowering the rotational speed of said receptacle below saidfirst perliminary centrifuging speed as required to redistribute saidfabrics within said receptacle, thereafter accelerating said receptaclewith the redistributed partially extracted fabrics to a second speedabove said preliminary speed, said second speed constituting a speedwherein the rotation of said fabrics vibrates said receptacle to apredetermined amplitude of vibration, interrupting acceleration of saidreceptacle above said second speed and providing and maintainingoperation at a constant intermediate centrifuging speed while applyingcounterbalancing mass to said receptacle to thereby reduce the amplitudeof vibration of said receptacle, said intermediate centrifuging speedbeing the speed at which the rotation of said fabrics vibrates saidreceptacle to a predetermined amplitude of vibration, and thenaccelerating said receptacle to still higher centrifuging speeds abovesaid second speed to extract additional uid from said fabrics.

5. The method of centrifugally extracting fluids from wet fabricscarried within a revoluble receptacle comprising, extracting the bulk ofabsorbed duid from said fabrics during a first period by acceleratingsaid receptacle to a preliminary centrifuging speed unmolested of anunbalance correction, thereafter decreasing the rotational speed of saidreceptacle during a second period to a tumbling speed below saidpreliminary centrifuging speed to redistribute said fabrics within saidreceptacle, thereafter accelerating said receptacle with theredistributed fabrics during a third period towards a high speed abovesaid preliminary centrifuging speed, interrupting the accelerationduring said third period in response to vibration of predeterminedmagnitude and maintaining the rotational speed at a constantintermediate speed while applying a counterbalancing mass to saidreceptacle to thereby reduce the amplitude of vibration of saidreceptacle, said intermediate centrifuging speed being the speed atwhich the vibration of predetermined magnitude occurs, and thenalternately repeating the accelerating and counterbalancing of saidreceptacle to increase the speed towards maximum speed above said speedduring the third period and extract residual absorbed fluid from saidfabrics.

6. The method of centrifugally extracting fluids from wet fabricscarried vwithin a revoluble receptacle comprising, extracting a portionof absorbed fiuid from said i3 fabrics by accelerating said receptacleto a preliminary centrifuging speed unmolested of an imbalancecorrection, decreasing the rotational speed of said receptacle belowsaid preliminaryv centrifuging speed to redistribute said fabrics withinsaid receptacle, accelerating said receptacle with the redistributedfabrics to a speed above said preliminary speed, interrupting saidacceleration when the rotation of said receptacle vibrates saidreceptacle to a first predetermined amplitude of vibration andmaintaining a constant first intermediate centrifuging speed Whiteapplying counterbalancing mass to said receptacle to thereby reduce theamplitude of vibration of said receptacle, thereafter accelerating saidreceptacle to a higher centrifuging speed above the previous speed,again interrupting the acceleration of said receptacle when the rotationof said fabrics again vibrates said receptacle to a second predeterminedamplitude of vibration and maintaining a constant second intermediatecentrifuging speed while applying' additional counterbalancing mass tosaid receptacle, and then accelerating said receptacle to still highercentrifugingspeeds above previous speed to extract additional residualabsorbed fluid from said fabrics, said first intermediate centrifugingspeed being the speed at which said first predetermined amplitude ofvibration occurs, and said second intermediate speed being the speed atwhich said second amplitude of vibration occurs.

improvement which comprises speed control means connecting with thepower drive means, time control means connecting with said unbalancedetecting means and with said speed control means and including firstswitch means connecting said time control means with said unbalancedetecting means, and second switch means connecting said time controlmeans with said speed control means, said speed control means operatingin connection with said time control means to impart a first relativelylow speed rotation to the container during a first period to remove thebulk of water therein and thereafter to reduce the speed of rotationduring a second period to a speed such that the clothes Within thecontainer rearrange themselves to a generally balanced condition, saidfirst switch means during said irst speed rotation being open to preventapplication of balancing corrections, said time control means afterclothes rearrangement regulating the increase of the speed of rotationof the container during subsequent periods towards a maximumcentrifuging speed, closing the iirst switch means and renderingeffective the unbalance detecting means, said latter means beingoperative during subsequent high speed rotation to actuate the baiancingmeans, and simultaneously through opening of the second switch means totemporarily maintain the rotative speed of the container at intermediatecentrifuging speeds corresponding to speeds at which unbalance isdetected while the balancing corrections are being made.

8. A laundry machine including a rotatable clothes basket, drive meansfor rotating said basket, said drive means being formed to acceleratesaid basket toward a maximum centrifuging speed and being also formed tooperate said basket at an intermediate centrifuging speed, sequencecontrol means causing said drive means to provide a centrifuging speedto said basket for a predetermined centrifuging cycle, means for sensingvibrations of said basket resulting from unbalanced distribution of theclothes therewithin during centrifuging thereof, and means responsive tosensing of vibrations of a predetermined magnitude to stop accelerationof said basket towards said maximum centrifuging speed and provide andmaintain operation at a constant intermediate centrifuging speed, saidconstant intermediate centrifuging speed i4 being the speed at which thevibrations of predetermined magnitude are sensed.

9. A laundry machine including a rotatable clothes basket, drive meansfor rotating said basket, said drive means including a variable speedbelt drive comprising a belt and a pair of rotatable sheave platesforming a groove between them, at least one of said sheave plates beingaxially movable relative to the other thereby to vary the distance fromthe center of rotation thereof at which said belt seats in said grooveso as to vary the output speed of said belt, means for moving at leastone of said sheave plates relative to the other so as to accelerate saidbasket toward a maximum centrifuging speed, means for sensing vibrationsof said basket resulting from unbalanced distribution of the clothestherewithin, and means responsive to sensing of vibrations of apredetermined magnitude to hold said sheave plates axially relative toeach other upon actuation of said sensing means thereby to provideoperation thereof substantially at the speed at which saidpredeterminedvibrations were sensed.

10. The apparatus defined in claim 9 wherein said means for moving atleast one of said sheave plates relative to the other comprise a gearmotor assembly.

11. A laundry machine including a rotatable clothes basket, drive meansfor rotating said basket including a variable speed belt drivecomprising a pair of rotatable sheave plates forming a belt-receivinggroove between them, at least one of said sheave plates being axiallymovable relative to the other thereby to vary the width of said groove,belt means seated within said groove at varying distances from thecenter of rotation of said sheave plates depending upon their axialposition relative to each other, electric motor means for moving atleast one of said sheave plates relative to the other to accelerate saidbasket toward a maximum centrifuging speed, means for sensing apredetermined magnitude of vibration of said basket resulting fromunbalanced distribution of the clothes therewithin, switch means havingiirst and second operative positions, said switch means having said rstposition prior to the sensing of vibrations of said predeterminedmagnitude, said sensing means moving said switch means to said secondposition thereof upon sensing vibrations of said predetermined magnitudeto stop said electric motor means and hold said sheave platesstationarily positionable positioned axially relative to each other uponactuation of said sensing means and stopping of said electric motormeans, said switch means operative to energize said motor in said firstposition thereof, and means rendering said switch means being operativein said second position only after a predetermined period ofacceleration to a minimum centrifuging speed to thereafter provide for acentrifuging operation at an intermediate spin speed corresponding tothe speed at which said vibrations of predetermined magnitude aresensed.

12. A laundry machine including a rotatable clothes basket, drive meansfor rotating said basket., drive control means formed to accelerate saidbasket toward a maximum centrifuging speed, means for sensing apredetermined magnitude of vibrations of said basket resulting fromunbalanced distribution of the clothes therewithin, means for stoppingacceleration of said basket towards said maximum centrifuging speed andproviding and maintaining operation thereof at a constant intermediatecentrifuging speed when said predetermined magnitude of vibrationsoccurs, said intermediate centrifuging speed being the speed at whichsaid predetermined magnitude of vibration is sensed, and means forslowing said clothes basket down for a redistribution of the clothestherewithin when a second predetermined magnitude of vibration occurs.

13. A laundry machine including a rotatable clothes basket, drive meansfor rotating said basket, said drive means being formed to acceleratesaid basket toward a maximum centrifuging speed and being also formed tooperate said basket at at least one intermediate centrifuging speed,sequence control means causing said drive means to provide acentrifuging speed to said basket for a predetermined centrifugingcycle, means for sensing vibrations of said basket resulting fromunbalanced distribution of the clothes therewithin during centrifugingthereof, and means responsive to sensing of vibrations of apredetermined magnitude to stop acceleration of said basket and provideoperation continuously at an intermediate centrifuging speed for theremainder of said centrifu ging cycle.

14. A laundry machine including a rotatable clothes basket, drive meansfor rotating said basket including a variable speed belt drivecomprising a pair of rotatable sheave plates forming a belt-receivinggroove between them, at least one of said sheave plates being axiallymovable relative to the other thereby to vary the width of said groove,belt means seated within said groove at varying distances from thecenter of rotation of said sheave plates depending upon their axialposition relative to each other, electric motor means for moving atleast one of said sheave plates relative to the other to accelerate saidbasket toward a maximum centrifuging speed, means for sensing apredetermined magnitude of vibration of said basket resulting fromunbalanced distribution of the clothes therewithin, switch means havingiirst and second operative positions, said switch means having saidfirst position prior to the sensing of vibrations of said predeterminedmagnitude, said sensing means moving said switch means to said secondposition thereof upon sensing vibrations of said predeterminedmagnitude, and means for retaining said sheave plates axially relativeto each other, said switch means being operative to energize said motorin said rst position thereof, means rendering said switch meansoperative in said second position only after a predetermined period ofacceleration to an appropriate minimum centrfuging speed to render saidretaining means effective thereafter thereby to provide for a cenl is?trifuging operation at an intermediate spin speed, said ap propriateminimum centrifuging speed being less than normal rated operationalspeed and said intermediate spin speed corresponding to the speed atwhich said vibrations of predetermined magnitude are sensed.

15. A laundry machine including a rotatable clothes basket, drive meansfor rotating said basket, said drive means including a variable speedbelt drive comprising a belt and a pair of rotatable sheave platesforming a groove between them, at least one of said sheave plates beingaxially movable relative to the other thereby to vary the distance fromthe center of rotation thereof at which said belt seats in said grooveso as to vary the output Spee-d of said belt, means for moving at leastone of said sheave plates relative to the other so as to accelerate saidbasket toward a maximum centrifuging speed, means for sensing vibrationsof said basket resulting from unbalanced distribution of the clothestherewithin, and means responsive to sensing of vibrations of apredetermined magnitude to retain said sheave plates axially relative toeach other thereby to provide operation thereof substantially at thespeed at which said predetermined vibrations were sensed it?. Theapparatus defined in claim i5 wherein said means for moving at least oneof said sheave plates relative to the other comprise a gear motorassembly, and said means for retaining said sheave plates inl apredetermined axial relation comprise means for retaining said gearmotor assembly against rotation.

References Cited by the Examiner UNITED STATES PATENTS 2,647,386 S/l953Keiper 210-144 X 2,760,639 8/1956 Haverstock 210-144 X REUBEN FRIEDMAN,Primary Examiner.

HERBERT L. MARTIN, Examiner.

3. THE METHOD OF CORRECTING UNBALANCE IN A ROTATING MEMBER SUCH AS ALAUNDRY CONTAINER COMPRISING THE STEPS OF FIRST ACCELERATING THECONTAINER TO A PRELIMINARY CENTRIFUGING SPEED TO EXTRACT A PORTION OFTHE FLUID IN THE ARTICLES, THEN SECONDLY ACCELERATING THE CONTAINER INROTATION TOWARD AN ESSENTIALLY FULL OPERATING SPEED FOR EXTRACTION OFOTHER FLUID PORTIONS, DETECTING UNBALANCE IN THE CONTAINER DURING THESECOND ACCELERATION, APPLYING CORRECTIVE BALANCING MASSES TO THECONTAINER WHEN AN UNBALANCE CONDITION IS DETECTED ONLY AFTER COMPLETIONOF SAID FIRST ACCELERATION STEP, TEMPORARILY TERMINATING THE SECONDACCELERATION OF THE CONTAINER WHEN THE UNBALANCE IS DETECTED ANDOPERATING AND MAINTAINING THE CONTAINER ROTATABLY AT A CONSTANTINTERMEDIATE CENTRIFUGING SPEED WHILE CORRECTIVE BALANCING MASSES AREBEING APPLIED, SAID INTERMEDIATE CENTRIFUGING SPEED BEING THE SPEED ATWHICH THE UNBALANCE IS DETECTED, AND IMMEDIATELY SLOWING THE ROTATION OFTHE CONTAINER TO A TUMBLING SPEED BELOW SAID PRELIMINARY CENTRIFUGINGSPEED WHEN AN EXCESSIVE UNBALANCE OF A PREDETERMINED MAGNITUDE ISREACHED.